Fluid gets Stuck in the Middle of Pipe
I'd try increasing the fluid domain resolution or switching from "preview" to "final" in both Viewport and Render Display (in the Fluid Domain options). 

It looks like the dimension of each fluid grid element is comparable to the section of the pipe, therefore a slight change to the pipe geometry can result in an obstruction for the fluid. Alternatively, you can make the pipe section larger.

If you're going to increase the resolution, do it little by little (around +20) or be aware that the simulation time and required memory can dramatically increase.